Tamper-indicating or tamper-evident packaging for food products and beverages assures consumers that products are fresh and unadulterated when purchased. U.S. Pat. No. 4,938,370, to McBride, illustrates a tamper-indicating plastic closure construction for use in connection with a bottle or like container having a threaded neck. The closure disclosed in this patent is particularly desirable in that two different modes of tamper-indication are provided, thus enhancing its tamper-resistance.
Specifically, the closure of this patent includes an annular pilfer band which is at least partially detachably joined to the bottom of a cylindrical skirt portion of an upper closure cap. For tamper-indication, the pilfer band includes a plurality of circumferentially spaced, relatively flexible tab elements which extend inwardly of the pilfer band for coaction with an annular locking ring on an associated container.
During application of the closure to a container, the flexible tabs are urged upwardly. When the closure is fully seated on the container, the tabs assume a more inwardly extending disposition, for coaction with the container locking ring so that the pilfer band is detached from the skirt portion during closure removal. Additionally, the pilfer band includes an annular interference bead positioned generally beneath the flexible tabs. In the event that the pilfer band does not initially detach from the closure skirt portion, by virtue of the tabs interacting with the container in their initial upwardly and inwardly extending disposition, the tabs can further function to cooperate with the interference bead. This is achieved by configuring the tabs and the interference bead to together provide a combined thickness which acts to reduce the effective inside diameter of the pilfer band, thereby providing the desired interfering engagement with the container locking ring for separating the pilfer band from the closure cap.
As will be appreciated, the upward flexing movement of the flexible tabs during closure application creates stresses on the closure, including stress on the frangible connection which detachably connects the pilfer band to the closure skirt portion. Attendant to high-speed application with modern bottling equipment, the stresses exerted on the frangible connection can be relatively high. This poses somewhat of a dilemma, in that the frangible connection must be configured to consistently and easily fracture and break attendant to closure removal, while at the same time be sufficiently strong to resist premature breakage during high-speed application.
The present invention contemplates an improved construction for a tamper-indicating closure of the above type, which construction facilitates high-speed closure application without compromise of the reliable performance of the closure.